1. Field of the Invention
The present invention relates to an apparatus for detachably connecting a tool to a manipulating device, comprising a tool holder and a coupling member mounted on the manipulating device, whereby the tool holder and the coupling member each include locking means to detachably connect the tool holder to the coupling device by a positive interlocking. Particularly, the invention relates to an apparatus of the kind referred to above which can be used as an interface for exchangeably mounting pneumatically and/or electrically operated tools on an industrial robot.
Automatically operating and computer-controlled manipulating devices gain an increasing importance in the field of manufacturing and handling of workpieces, particularly in series production, for instance in the field of mounting or assembling of various devices and parts, in the field of placing electric and electronic components on a printed circuit board or a similar substrate etc. Such manipulating devices usually comprise a tool holder on which a tool is mounted which can be moved, within certain constructional limits, in several degrees of freedom and which serve to treat the workpiece. It should be pointed out in this connection that the expression "tool" shall be understood in its broadest sense; not only working tools like drilling machines, power operated screw drivers etc. are meant, but also gripping pliers, vacuum grippers, means for applying adhesive to a workpiece, measuring and test instruments, loading and unloading devices for workpiece pallets etc.
As long as such a manipulating device has to meet only one job, e.g. taking a part out of a magazine and putting it into a workpiece which passes the manipulating device, the mounting of a tool suitable for this job on the arm of the manipulating device does not present any problems. However, if only comparatively small series have to be treated, or if a certain manipulating device has to meet several different jobs, it should be made sure that a rapid tool exchange without any problems can be performed, if possible in a fully automatic manner.
2. Prior Art
For this purpose, an apparatus is disclosed in U.S. Pat. No. 4,636,135 which comprises a coupling member mounted on the arm of a robot and a tool holder which can be positively locked in the coupling member and which is detachable from the coupling member. Since many tools, e.g. gripping pliers, are pneumatically or electrically operated, the coupling member is provided with a connection for pressurized air communicating with an air outlet provided in the tool holder as soon as the latter one is connected to the coupling member. Furthermore, the coupling member and the tool holder are provided with electric connectors adapted to engage upon mounting the tool holder on the coupling member. Thus, it is possible to prepare the tool holder by mounting e.g. an pneumatically or electrically operated tool on the tool holder in advance and to establish the required air and/or electric connection between tool and tool holder.
However, two problems can not or only partly be solved with the apparatus according to the above mentioned U.S. Pat. No. 4,636,135: On the one hand, such an apparatus is not universally usable but is suited only for such pneumatically operated tools which require only a single air supply connection. Further connections, e.g. an additional connection for the supply of pressurized air or a connection to a vacuum source have to be realized in addition; this results in the fact that such an apparatus is not suitable for an automatic tool exchange. On the other hand, the positioning accuracy, particularly the repetitive positioning accuracy, of the tool holder with respect to the coupling member and, thus, to the manipulating device is not satisfactory. Because manipulating devices according to the latest state of the art are able to be operated within a preset target range of 0.05 mm, even if the arm of the manipulating device has to be returned to the same target position repetitively, it is very important that the position of the tool with respect to the arm of the manipulating device is exactly defined and maintained also after an automatic tool exchange. This is of primary importance if the manipulating device effects a plurality or a series of different operations whereby the tool must be exchanged after each operation.